Electric fuse plug and fuse



- Par-shied Aug. 11, 1942 UNITED STATES PATENT OFFICE ELECTRIC FUSE PLUG AND FUSE Joseph Sperlinz, New York, N. Y.

Application April 2, 1941, Serial No. 386,405

12 Claims.

This invention relates to new and useful improvements in electric fuses and more particularly it pertains to fuses of the type in which the fuse element may be replaced or renewed after it has served its purpose.

It is the object of the invention to provide electric fuses which are simple of construction,.

eflicient in operation and which may be operated to renew the fusible element without requiring special skill or knowledge upon the part of the operator.

In the present application 1 have illustrated the invention as embodied in three difierent types of electrical fuses, namely the plug type, ordinary cartridge type andknife terminal cartridge type, but it is to be understood that the invention may also be employed in any of fuse where it is desirable to obtain the advantages resulting from its use.

A feature of the invention resides in the provision of a substantially. solid main body portion by which the fuse element is carried. in relative close confinement and by which more positive electrical connections may be obtained.

Another feature of the invention resides in a novel construction of parts whereby the fuse element may be inspected without removal of the fuse from an electrical socket. This feature I consider important since with fuses of the plug type as generally constructed, it often becomes necessary to remove the fuse to determine whether it has been burned out. Where there are many fuses in. a group, each good fuse removed to determine its condition results in the interruption of the circuit in which that fuse is embodied, thus causing considerable annoyance and inconvenience. With my plug type fuse, condition of the fusible element may be ascertained without removing the plug from the socket and therefore without unnecessarily interrupting the circuit in which it is embodied.

Another feature of the invention'resides in the provision of a main body portion which is substantially solid. in form as distinguished from the shell and tubular types of body portions heretofore employed.

Still another feature of the invention resides in a novel construction whereby the fuse element may be closely confined within the body portion, thus affording protection against accidental rupture thereof.

As heretofore stated, the fuses herein illustrated are of the type in which the fuse element is renewable and a further feature of the invention resides in a novel construction whereby the 55 fuse elements may be easily placed in position or removed and replaced when necessary.

Other features of the invention will be readily apparent as the nature of the invention is better understood for which purpose reference will now be had to the accompanying drawing and the following specification, wherein the invention is illustrated and described.

In the drawing:

Figure 1 is a distended perspective view illustrating a fuse of the plug type constructed in accordance with the present invention.

Figure 2 is a vertical sectional View through the fuse with the several parts in their assembled position,

Figure 3 is a perspective view of the fuse ele ment employed in the plug type fuse showing the element in dotted lines in its form before it is bent for placement in the fuse plug,

Figure 4 is a perspective view of a cartridge type fuse constructed in accordance with the present invention,

Figure 5 is a transverse sectional view on an enlarged scale taken substantially on the line 5-5 of Figure 4:,

Figure 6 is a longitudinal sectional view on an enlarged scale of the cartridge type fuse,

Figure 7 is a plan view of the fuse element employed in the cartridge type fuse,

Figure 8 is a fragmentary sectional view ii lustrating a modified form of the invention and showing it applied to a fuse of the knife terminal cartridge type, and

Figure 9 is a perspective view of one'of the elements employed for securing the fuse element in position in the type offuse illustrated in Figure 8.

Referring in detail to the drawing, and particularly to Figs. 1 to 3, the fuse is designated by the reference character A.

@The fuse comprises a body portion it which is formed from fibre, porcelain or other suitable non-conducting material. The body portion It is solid in form and has a shallow recess ii in its outer end. The body portion II] is provided with the ordinary metal cap i3 which is threaded to provide for removable placement of the plug in an electrical socket. The inner end of the body member 10 is designated l4 and it is provided with a screw threaded recess IS, the purpose of which will be hereinafter described. The recess 15 extends from a countersunk portion i6 and leading from the base of the countersunk portion to one side of the center of the body portion [0 there is a relatively small passage l1. The

outer end of the passage l1 terminates in the bottom wall of the recess I I and leading from the recess H to a point diametrically opposed. with respect to the passage ll there is a passage l8.

The passage l8 emerges at the side of .the body portion Ill at which point there is a threaded recess 19, the purpose of which will be hereinafter described.

The reference character 20 designates the fuse element and it comprises an elongated strip of suitable fusible material weakened intermediate of its ends as at 2| in the ordinary manner. At one end the strip is provided with an opening 22 and at its other end with an opening 23. The fusible element is also notched as at 24 adjacent the opening 22 and as at 25 adjacent the opening 23.

The fuse element is bent transversely along the lines 25 and 21 to provide a main body portion 23 from which extend two legs 29 and 30. The leg 28 is of greater length than is the leg 38 and these legs are adapted to be received respectively in the passages H and Hi, the fuse element after being bent as heretofore described, being inserted into the solid body portion it through the recess H thereof.

In order that the fusible element may be inserted as heretofore described, the outer end of the recess i I is provided with a threaded portion 3| for the reception of a threaded plug 32. It will be noted that the outer end of the plug 32 is provided with a knurled or otherwise roughened surface 33 which provides gripping means whereby the threaded plug may be manipulated to position it in, or remove it from the recess l I. This plug 33 has one or more, small vent passages or ports 34 extending therethrough which establish communication between the recess H and atmosphere when the plug is in position in the solid body member Ill.

To assemble the fuse the plug 32'is removed and the fuse element 20 is bent upon the lines 26 and 21. With the fuse element thus formed it is inserted into the recess II with its leg 29 in the passage l1 and its leg 30 in the passage l8. These passages l1 and l 8being of relatively small transverse dimensions serve to guide the legs of the fuse element to their proper position. After the fuse element has been thus positioned, it is bent upon lines connecting the notches 25 in such a manner that the openings 22 and 23 in the le s of the fuse element will coincide respectively with the threaded recesses l and I9 in the body portion Ill.

The fuse element is secured in osition bv means of threaded members 35 and 40. Each o these threaded members has an enlarged disc-like head 4| which engages its respective end of the fuse element clamping it in position to retain the fuse element ri idly in proper position within the body portion Hi. It will be noted that the enlarged disc-like head 4| of the threaded membe I 9 engages the metal cap l3 within a countersunk portion thereof and clamps the end of the leg 30 of the fuse element in electrical contact therewith. I

With the fuse thus assembled, if it be inserted in an electrical socket of conventional form, the threaded members 35 and 40 form respectively electrical contacts with the center and side terminals of the socket.

From the foregoing, it will be apparent that when the fuse is assembled, the fuse. element will have its main body portion 29 positioned in the recess H and its legs 29 and 30 in the narrow channels H and I8.

When'the fuse is assembled in an electric circult" the circuit passes from the threaded element 35 through the fuse element to the threaded element 40. In case of an overload the fuse element is ruptured 'by burning out, the gases escaping from the recess I! through the passages or ports 34.

It will be noted that a fuse constructed in accordance with the present invention has many advantages over fuses as generally constructed since it provides for the renewal of the fusible element merely by removing the plug 32 and the threaded elements 35 and 40 in order that a new fuse element may be positioned in the manne'r heretofore described.

In addition to providing for removal of a ruptured fuse element and its replacement, the plug 32 serves an additional purpose. For example, if it is desired to inspect the fuse while in use to determine whether the fuse element is in good condition, it is only necessary to remove the plug 32 from the body portion ill, whereupon the fuse element will be exposed as illustrated in Fig. 1. This is an important feature since it permits of ready inspection of the fuse to determine the condition of its fuse element when the fuse is in operative position in an electriclcircuit without interrupting the circuit if the fuse has not been ruptured.

In Figures 4 to 7, I have illustrated a fuse of the body portion 45 there is a cap 46 which is retained in position upon the ends of the body portion 45 by upsetting portions 41 of the cap into suitable recesses 48 in the body portion 45.

These caps 45 form the contact elements of the fuse and each is provided on its outer face with a recessor countersunk portion 49 and an opening 50.

Extending longitudinally through the body portion 45 in slightly offset relation with respect to the axis thereof, there is a passage 5l of relatively small transverse dimensions. Leading from the passage 5| there are passages or ports 52 which establish communication between the passage 5! and atmosphere.

The fuse element is illustrated in Figure 7 and is of substantially the same type as that heretofore described, having end portions 53 provided with openings 54 which are adapted to be bent to position at right angles to the main body portion along lines connecting notches or the like 55. l;

The fuse element which is designated 56, is threaded through the passage 5!. By reason of the relatively small transverse dimension of the passage 5! the fuse element is easily passed to position with its ends 53 projecting beyond their respective ends of the body portion 45. With the fuse element in this position the end portions 53 are bent as heretofore described, bringing their openings 54 into registration with internally threaded recesses 60 in the ends of the body portion 45, the fuse element passing through relatively small slots 6| in the caps 46 which openings register with their respective ends of the passage 5| as best illustrated in Figure 6. With the fuse element thus positioned threaded cesses 60, clamping the ends 53 of the fuse elements against the bottom wall of their respective recesses 49.

From the foregoing construction, it will be obvious that the fuse element will be retained in operative position within the solid body 45 and that a good electrical contact will be established between the fuse element and the caps 46. In addition to providing this electrical contact, the

threaded elements 63 may serve also to rigidly retain the caps 46 in position upon the body member 45.

In fuses of this type it is only necessary to remove one of the threaded-members 63 to determine whether the fuse element has been ruptured. For example, if the fuse element has become ruptured, upon removal of one of the threaded elements 63 a section of the fuse element will drop out of the passage In this case, the other threaded element 63 is removed and a new fuse element is substituted for the one ruptured. If, however, the fuse element has not been ruptured, it cannot be removed from the body portion upon the removal of but one of the threaded elements 63 and this condition will indicate that the fuse element has not been ruptured.

Fuses of the cartridge type, particularly in the smaller sizes, are awkward in their placement and displacement relatively to the spring contacts in which they are mounted.

It will be noted by reference to Figs. 4 and 6 that I provide an integral projection extending radially from the main body portion 55 at a point intermediate of its ends, which point is diametrically opposed with respect to the ports or passages 52. This projection provides a manipulating handle by means of which the fuse may be placed within, or removed from its spring contacts without danger of shock upon the part of the person so doing.

In Figs. 8 and 9 I have illustrated a fuse of the knife terminal cartridge type.

In this type of fuse the body member end caps and fuse element are of substantially the same construction as in the form illustrated in Fig. 6.

The contact elements, however, are different in that they comprise an intermediate body portion ll of disc-like form. The blade element 18 projects from one face of the main body portion ii and projecting from the other face of the body portion li there is a threaded member 19 for threaded engagement with the recess 6!! of the body member 45;

The body portion 11, the blade 18 and the threaded extension 19 are all formed from one piece of material and when placed in the position illustrated in Fig. 8 it will be noted that the body portion H serves to clamp the end of the fusible element against'the bottom wall of the countersunk portion 80 of the cap hi to provide a good electrical contact between the fuse element and the contact element. In this form of the invention the contact element may also be employed element in a relatively small slot, acts to smother any flame resulting from the burning out of the fusible element and obviates the necessity of fillers or other means for accomplishing this result.

From the foregoing it willbe apparent that the present invention provides a new and novel fuse, in which the fusible element of a plug type fuse may be inspected without removal of the fuse from a socket and without interruption of the circuit of which it is a part and further, that the fusible element of the fuse "may be readily renewed in an easy and convenient manner.

Having thus described the invention, what is claimed is:

1. An electrical fuse comprising a main body portion of solid form, a threaded portion Providing means for mounting the fuse in an electric socket, an internally threaded recess extending to retain the cap in position upon the body mem- In the last described form of the invention the condition of the fusible element is determined in the same manner as described for the form illustrated in Figs. 4 to '7 and its replacement is accomplished in the same manner.

In both forms of the invention as illustrated in Figs. 4 to 9, the close confinement of the fuse inwardly of the outer end of the solid body portion, a slot of relatively small transverse dimensions extending through said body portion and across the internally threaded recess, means for anchoring the ends of the fuse element and for.

forming terminal contacts therefor, and a plug removably threaded in said internaly threaded recess.

2. An electrical fuse comprising a main body portion of solid form, a threaded portion provid= ing means for mounting the fuse in an electric socket, an internally threaded recess extending inwardly of the outer end of the solid body por tion, a slot of relatively small transverse dimensions extending through said body portion and across the internally threaded recess, means for anchoring the ends of the fuse element and for forming terminal contacts therefor, and a plug removably threaded in said internally threaded recess,,the inner end of said plug being spaced with respect to the fuse element.

3. A fuse of the type described comprising a solid body portion having an exteriorly screw threaded portion for mounting the fuse in an electric socket, a recess in the outer end of the body portion, a fuse element carried by the body portion and extending from the outer face of the exteriorly threaded portion through a relatively small passage to the recess in the outer end of the solid body portion, across said recess and through a second passage through the body portion to the exteriorof the threaded portion atone side there of, means for anchoring the ends of fusible element to the body portion enceriorly of their respective slots, and a closure element removably mounted in the recess in the outer end the solid body portion.

4. A fuse of the type described comprising a solid body portion having an exteriorly screw threaded portion for mounting t .e fuse in an electric socket, a recess the outer end of the body portion, a fuse element carried the body portion and extending from the outer face of the exteriorly threaded portion through a relatively small passage to the recess in the outer end of the solid body portion, across said recess and 5. An electric fuse comprising a solid body member of elongated cylindrical form having a relatively small passage extending longitudinally therethrough from end to end, a fusible element carried by the body member in the longitudinally extending passage thereof, contact elements for said fusible element, means for securing the fusible element to its contact elements, vent passages leading radially from said longitudinally extending passage to atmosphere, and an operating handle projecting radially from the exterior of the body member from a point diametrically opposed with respect to said vent passages.

6. An electrical fuse comprising a solid body member of elongated cylindrical form of nonconducting material, a fuse passage extending longitudinally of the said body, a plurality of vent passages leading from said'fuse passage to atmosphere, and a manipulating member projectin radially from the exterior of said body in oppositely disposed relation to said vent passages.

'7. An electric fuse comprising a solid body member of elongated cylindrical form having a relatively small passage extending longitudinally therethrough from end to end, saidpassage extending parallel with the longitudinal axis of the body portion and being ofi-set with respect thereto, end caps of suitable conducting material adapted to receive the ends of the solid body member, each of said end caps having a slot adapted for registration with its respective end of the passage through the body portion, a fusible clement carried by the body portion in the longitudinally extending passage thereof and extending through the slots in said caps, and means for securing the fusible element to the caps.

8. An electric 'fuse comprising a solid body 9. An electrical fuse of the knife type comprising a solid main body member of elongated cylindrical form, a fuse element extending longitudinally throughsaid body member, said fuse element being of greater length than the length of the body member, whereby the fuse element may have its ends bent into positions at right angles to the main body portion thereof, and blade-like contact elements for securing the fuse element to the main body member of the fuse and for forming electrical contact with the fuse element.

10. An electrical fuse of the knife type comprising a solid main body member of elongated cylindrical form, a fuse element extending longitudinally through said body portion, said fuse element being of greater length than the length of the body member, whereby the fuse element may have its ends bent into positions at right angles to the main body portion thereof, and blade-like contact elements for securing the fuse element to the main body member of the fuse and for forming electrical contact with the fuse element, each of said contact members comprising an intermediate disc-like member for clamping one end of the fuse element to the main body member of the fuse, and providing electrical connection between the contact member and the fuse member of "elongated cylindrical form having a relatively small passage extending longitudinally therethrough from end to end, said passage extending parallel with the longitudinal axis of the body portion and being off-set with respect thereto, end caps of suitable conducting material adapted to receive the ends of the solid. body member, each of said end caps having a slot 7 ad'apted for registration with its respective end of the passage through the body portion, a fusible element carried by the body portion in the longitudinally extending passage thereof and extending through the slots in said caps, and means for securing the fusible element to the caps, said means comprising a fastening element passing through each end of the fusible element and its respective cap and having threaded engagement with its respective end of the body member.

element, a blade projecting from one face of the disc-like member, and a, threaded extension projecting from the opposite face of the disc-like member for threaded engagement with the end of the main body member of the fuse.

11. A fuse of the type described comprising in combination, a main body portion of solid form having a slot of relatively small transverse dimensions extending therethrough, a fuse element closely confined in the slot of the body portion and removable means for securingthe ends of the fuse element to the body portion on the exterior thereof. g

I 12. A fuse of the type described comprising in combination, a main body portion of solid form having a slot of relatively small transverse dimensions extending therethrough, a fuse element closely confined in the slot of the body portion, said fuse element terminating in angularly disposed ends upon the exterior of the body portion, and removable means for threaded engagement with the body portion for securing the ends of the 

